In an eye, accommodation is a process whereby the eye adjusts focus from far to near to allow for clear viewing at multiple distances. Accommodation involves the ciliary muscle or body, zonules, capsular bag and the crystalline lens. The ciliary muscle is a circumferential sphincter muscle that lines the inside of the eye and adjacent to the eye wall. When the ciliary muscle contracts, it moves inward towards the center of the eye and when the ciliary muscle relaxes it moves outward towards the eye wall.
The ciliary muscle is connected to zonules. Zonules are attachment ligaments that attach to the ciliary muscle peripherally, and to the periphery of the capsular bag which encompasses the crystalline lens, centrally. Thus, the ciliary muscle, zonules and crystalline lens are connected, and movement of one causes movement of the others.
The crystalline lens is a disc-shaped viewing and refracting component of the eye. The lens is enveloped by the capsular bag. The lens and capsular bag are highly elastic and change shape with external compressive or deforming forces. The natural resting shape of the crystalline lens is a rounded disc shape. This shape, known as the accommodated state, has higher refractive power and provides clear viewing of nearer objects. The lens may be pulled centrifugally, via the zonules, by the ciliary muscle into a sagittally flatter shape, i.e., the unaccommodated state. The flatter shape has lower refractive power and provides clear viewing of more distant objects. Incremental changes in between the two shapes provides for smooth transition between distance and near viewing. When the ciliary muscle is in a relaxed state, the crystalline lens is pulled into its flatter shape for distance viewing. When the ciliary muscle contracts, the crystalline lens is allowed to relax into its more rounded shape for near viewing.
Presbyopia, or loss of accommodating ability with age, develops due to several factors. The crystalline lens loses elasticity with age, thereby losing the ability to resume the more rounded shape with age. While ciliary muscle continues to contract, the lens no longer responds as it once did. Also, there is recent evidence from high resolution MRI studies indicating that the ciliary muscle circumference may decrease with age, while the crystalline lens equatorial circumference remains fairly stable in adulthood. This causes a decrease in the distance between ciliary muscle and equator of lens and a concomitant decrease in zonular tension. Thus, with age when the ciliary muscle contracts and relaxes, its force is not as effectively transferred to the lens due to the laxity in the zonules.
Cataract, or the clouding of the crystalline lens, may also adversely affect vision. Cataract causes obstruction and a decrease of vision. The current form of treatment of a cataract is the removal of the cataract and implantation of an artificial intraocular lens. Artificial intraocular lenses typically come in three forms: monofocal; multifocal; and accommodating.
The monofocal lenses have a single refractive power providing the patient with clear, unaided vision at one particular viewing distance; however, refractive correction is required for viewing at other distances. Multifocal lenses are one attempt at providing clear vision at multiple distances. Multifocal lenses sometimes result in undesirable side effects, such as dim light glare, halos and loss of contrast sensitivity. Accommodating lenses are another attempt at providing clear vision at multiple distances. While accommodating lenses do not typically have the side effects of multifocal lenses, most accommodating lenses have not been very effective. Therefore, there exists a significant need for an improved accommodating intraocular lens.
In particular, this application discloses an intraocular lens comprising: an adjustable optic, the optic capable of being moved between an accommodated state and an unaccommodated state, the optic comprising: an anterior portion; a posterior portion; a sidewall between the anterior portion and the posterior portion; a ring disposed about the optic sidewall; and a haptic coupled to the ring, the haptic capable of being coupled to a patient's capsular bag.
This application also discloses an eyelet for coupling an intraocular lens to a capsular bag of a patient, the eyelet comprising: a first portion comprising: an annular body; a lip disposed about a first end of the first portion annular body, the lip operable to abut an exterior surface of the capsular bag; a second portion comprising: an annular body; a lip disposed about a first end of the second portion annular body, the lip operable to abut an interior surface of the capsular bag; wherein at least one of the first portion and second portion is configured to lockingly engage the other one of the first portion and second portion when at least a portion of the capuslar bag is disposed between the first portion and second portion.
This application further discloses a method for implanting an intraocular lens in a capsular bag of a patient's eye from which the natural lens has been removed, the method comprising: installing an intraocular lens within the capsular bag, the intraocular lens comprising: an adjustable optic, the optic capable of being moved between an accommodated state and an unaccommodated state, the optic comprising: an anterior portion; a posterior portion; a sidewall between the anterior portion and the posterior portion; a ring disposed about the optic sidewall; and haptic coupled to the ring; installing an eyelet in the capsular bag; stretching the intraocular lens; and coupling the lens haptic to the eyelet.